Relevance of the research. Ageing is a multi-factorial process that ultimately induces a decline in physiological functioning, causing a decreased health-span, functional mobility and quality of life (Capodaglio et al., 2005). Exercise participation is recommended to reduce the impact of ageing through maintenance of physiological parameters (Gault, Willems, 2013). Eccentric endurance exercise in the form of downhill treadmill walking (DTW) at a self-selected speed produces a lower cardiovascular stress for older adults in comparison to level treadmill walking (LTW) (Gault et al., 2013).This is because the muscles produce a force whilst lengthening during DTW, which also causes muscle injury when unaccustomed (Gault et al., 2011). Such an exercise model could be ideal for improving functional mobility of older adults, due to the muscles ability to combine high muscle force production with a lower energy cost.

The object of the research was to examine the adaptations of older adults to a novel endurance exercise model, the aim was to assess functional adaptations to a concentric (LTW) and eccentric endurance exercise (DTW) programme at a self-selected intensity.

Results and discussion. Both LTW and DTW improved performance in functional tasks by up to 34 % for all older adults (5-RSTS: +34 %; MWS: +23 %; TUG: 22 %). There was however no improvement in peak concentric or eccentric torque of the knee extensors or flexors, but an improvement in maximal voluntary isometric force (MVIF) and 5 % of MVIF steadiness. The increase in MVIF for LTW was the result of a 38 % increase in EMG rms of the m. vastus lateralis, with no changes in EMG observed for the DTW group, suggesting a different adaptation. As a result of both LTW and DTW, older adults also improved their aerobic capacity with up to a 23 % improvement in predicted O2max.

Conclusions. Regular LTW and DTW by older adults at a SSWS results in an improved functional mobility, isometric strength and steadiness, and aerobic capacity. The potential implications for an exercise modality such as DTW, with a lower oxygen demand, to improve muscle strength and aerobic capacity could serve as a rehabilitative countermeasure for older adults.